Incandescent lamp



Dec. 20, 1938, H. E. ALLEN INCANDESCENT LAMP Filed July 16, 1957ATTORNEY Patented Dec. '20, 1938 UNITED STATES INCANDESCENT LAMP HowardE. Allen, Nutley, N. 1., assignor to wet. inghouse Electric aManufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvanla Application July 18, 1937, Serial No. 153,918 13 Claims.(Cl. 176-39) 'I'his invention relates to incandescent electric lamps andmore particularly to such adapted for projection service and employingcoiled filaments as light sources.

The principal object of my invention, generally considered, is theprovision of an electric lamp adapted for projection-service, and havinga coiled filament so mounted therein that strains in said filament dueto changes in temperature are substantially eliminated.

Another object of my invention is the elimination of strains due toexpansion and contraction of lamp parts, such as the inner leads andsupports, to avoid filament distortion which is apt to occur, especiallywhen lamps are subjected to intermittent operation.

A further object 01. my invention is the provision of a lamp,particularly adapted for projection service, said lamp having a coiledfilament mounted between inner leads which are threaded through loops atthe upper ends of a guiding bridge secured to lower portions of saidfilament, the upper portions of the filament being suspended from aninsulator connecting the upper ends of the leads.

A still further object of my invention is the provision of means foreliminating strains due to temperature changes in a lamp having a coiledfilament, comprising the employment of a light bridge assembly suspendedfrom the bottom of the filament, having arms extendingverticallyupwardly or diagonally upwardly and outward and slidable onthe leads which support the filament, and a bottom member slidabiyguided with respect to the stem, in order to prevent tilting when thelamp is operated in a position other than vertical.

Another object of my invention is the provision of braces or tie wiresto prevent distortion of the inner supporting leads at a point adjacentor slightly above the stem press.

Other objects and advantages of the invention, relating to theparticular arrangement and construction of the various parts, willbecome apparent as the description proceeds.

Referring to the drawing illustrating my invention:

Fig. 1 is a side elevational view of a projection lamp embodying myinvention, with portions of the envelope or bulb broken away to moreclearly show the interior construction.

Fig. 5 is a view corresponding to Fig. 4, but showing another embodimentof said guide.

Referring to the drawing in detail, like parts being designated by likereference characters, and first considering the embodiment of myinvention shown in Figs. 1 to 4 inclusive, there is disclosed a lamp i0comprising an envelope or bulb II, with a base indicated at l2, andenclosing a mount l3.

The mount of the present embodiment comprises a flare tube l4, sealed tothe bulb and provided with an exhaust tube l5, and an arbor or buttonit, extending from a press l1. Leading-in conductors l8 and i9 extendthrough the press from the base l2 and connect with relatively rigidinner supporting leads 20, which may be formed of nickel, or othersuitable material, with their normally lower ends imbedded in the pressII.

In order to further rigidify the connection between the inner supportingleads and the press I1, I provide wires 2| and 22, ends of which areimbedded in the arbor l6, as indicated at 23 and 24, and which extendoutwardly therefrom and are wound around the leads 20 to which, afterone or more turns, they are spot-welded, as indicated at 25 and 26. Byusing this construction,

- breakage or distortion is avoided, as the embrittled portions of thewires 2| and 22 (which are desirably formed of molybdenum) which developduring the welding process, are removed from the portions subjected tothe direct strain where the wires contact the supporting leads 20.

One reason for this desired rigidification is that these nickel leads20, regardless of original stifiness, are softened during the stemmaking process up to a point several millimeters above the press, sothat they would be apt to bend easily when subjected to shock. Thistying of the leads to the upper portion of the button or arbor IS, inthe manner just described, greatly strengthens and rigidifies theconstruction.

In the present embodiment, the normally upper or free ends of thesupporting leads 20, are connected by wires 21 and 28, the outer ends01' which are spot-welded thereto, as indicated at 29 and 30, and theinner ends of which are imbedded in an insulating member 3l'which may bea piece of glass cane.

Depending from the insulator 3] are a plurality of supporting members32, 33, 34, 35, and 36, the number depending on how many coil sectionsthe filament 31 is formed with. In the present embodiment, the coilfilament 31 comprises eight coil sections which are connected byinter-section loops and staggered, so that four are disposed in onenormally vertical plane and four in a normally vertical plane parallelthereto and so spaced that in plan they lie at the vertices of isoscelestriangles. The upper of binding, even when the bridge device is slighttoimprove the uniformity 'of rating.

In .order to hold the filament 31 in position between the-leads 20, andat the same time eliminate strains due to the expansion and contractionof the metal parts in the lamp, I provide a light bridge assembly 44,which may comprise an insulating portion 45 formed of a piece of glasscane, and end wires 46 and 41, the inner ends of which are imbedded inthe insulator 45 and the outer ends of which normally extend diagonallyor longitudinally outward and are upward and formedwith eyesor loops 48and 49 to receive the supporting leads 20. The eyes or loops 48 and 49are adjusted so as to slide freely on the leads 20 with the avoidance lytilted with respect-to said leads.

The bridge device 44 is normally. suspended from the filament 31 byhaving members 50, 52, and 53, the lower ends otwhich are imbedded inthe insulator 45 and the upper ends of which are bent to hook over theloops formed between the lower portions of the coiled sections offilament 31.

In order to prevent undesired tilting of the bridge device 44 when thelamp is inclined from its normally vertical base-down position, theinsulator 45 is provided with a bottom guide 54 cooperating with a wire55 extending upwardly from the arbor IS. The member 54 may be providedwith an eye or'loop 55 in which the wire 55 slides, for guiding thebridge member during a thermal expansion or contraction of, the parts,or the construction may be reversed, as illustrated in Fig. 5 with theeye or loop portion 56'" provided on the member '55, extending from thearbor I5, and the member 54 which extends from the insulator 45, beingstraight. In both instances, however, the straight member is,after'assembly, bent-over, as indicated at 51 in Fig. land 51 in Fig. 5,in order to prevent disengagement, leaving, however, ample clearance forthe desired amount of expansion and contraction.

The hook portions of the members 50 to 53 inclusive, aredesirably solong that even when the lamp is positioned base-up, they would not be--come disengaged even upon movement of the loop or eyelet 55 intoengagement with the bent-over portion 51 of the guiding wire .55. Themember 54 is desirably curved, as illustrated in Figs. 2 and 4, to clearthe guiding wire 55, except where its eyelet 56 slides therearound.

From the foregoing disclosure it will be seen that. I have developed onincandescent lamp,

particularly adapted for projection purposes, in

which normally upper portions of the coiled filament are supported in arelatively rigid manner, .while the normally lower portions carry alight bridge .device having side loops,'which slide freely on the innersupporting leads, and a lower slidable connection with the arbor of themount,-

guide member.

avoided, and the loops which slide on the supporting leads are so largeand so far removed from the. insulating portion of the bridge, by

being positioned at the ends of the diagonally, axially or verticallydisposed wires, that binding is avoided even if a slight amount oftilting occurs. In this way filament strains, due to expansion andcontraction of lamp parts, are avoided, and filament distortion reducedto a minimum, thereby eliminating one source of erratic life andpoorlumen maintenance.

It will also be noted that I have provided means for eificientlybracing. the inner supporting leads from the arbor of the lamp.

Although preferredembodiments of my invention have been disclosed, itwill be understood that modifications may be made within the spirit andscope of the appended claims.

I claim:--

1. An incandescent electric lamp comprising interior supporting leads, acoiled filament disposed therebetween, and means supported by and belowsaid filament, and with members extending longitudinally outward andupward to the filament level, and slidable on said leads for eliminatingfilament strains due to the expansion and from an intermediate portionof said slidable means to prevent undesired tilting thereof.

2. An incandescent electric lamp having a mount comprising a flare tube,interior supportingleads extending therefrom, a coiled filament disposedtherebetween, and means secured to, and normally disposed below, saidfilament and formed with extensions slidable on said leads, on oppositesides and at about the same level as the filament, for eliminatingfilament strains due to the expansion and contraction of lamp parts, andmeans guidably mounted with respect to said mount and forming a thirdpoint of support to prevent undesired tilting of said slidable means.

3. An incandescent electric lamp having a mount comprising a flare tube,interior supporting leads extending therefrom, a filament comprising aplurality of coils with their axes gen- "erally parallel and disposedbetween said leads,

means securing one set Minter-section loops between said leads, andmeans disposed normally below and attached to the other set ofintersection loops and formed with guides extended outwardly and in anormally upward direction, and slidable on said leads for holding saidfila- -ment in place and eliminating strains therein due to expansionand contraction, and means extending ina normally downward direction toform a supplemental guide and prevent undesired tilting of said slidablemeans.

' 4. An incandescent electric lamp comprising a mount with a fiare tube,interior supporting leads ment receiving energy through wires extendingfrom said leads, toward one another, and to which the-ends of saidfilament are connected, and a guiding member comprising an insulatorportion, hook portions extending from said insulator portion andconnected to the normally lower filament loops, wires extending from theends of said insulator and with their free end portions slidable on saidsupportingleads, and a member extending from the side of said insulatorportion, in a direction opposite to that of said hook portions, toprevent undesired tilting of said contraction of lamp parts, and meansextending leads, .said filament receiving energy through wires extendingfrom said leads, toward one another, and to which the ends of saidfilament are connected, and a guiding member comprising an insulatorportion, hook portions extending from said insulator portion andconnected to the normally lower filament loops, and wires extending fromthe ends of said insulator and with their free end portions slidable onsaid supporting leads, said insulator having a depending guide memberslidably associated with a wire upstanding from said arbor.

6. An incandescent electric lamp comprising a mount with a flare tubeand an arbor, interior supporting leads extending from. said tube, afilament comprising a plurality of coil sections with their axesdisposed generally parallel, said sections being connected by loopportions and supported from said leads by wires depending from aninsulator tied to the ends of said leads, with the lower portionsthereof hooked under the normally upper filament loops, said filamentreceiving energy from said leads through wires extending toward oneanother and fitting into coiled end sections of said filament, and aguiding bridge member comprising an insulator portion, hook portionsextending from said insulator portion and receivedv in the normallylower filament loops, wires extending from the ends of said insulatorand formed with eyes at their ends slidable on said supporting leads,said insulator having a depending guide member slidably associated witha wire upstanding from said arbor.

'7. An incandescent electric lamp comprising a mount with a fiare tubeand an arbor, interior supporting leads extending from said tube, afilament comprising a plurality of coil sections connected by loopportions and supported from said leads, said filament receiving energyfrom said leads by having their ends connected thereto, and a guidingmember comprising an insulator portion, wires extending therefrom andconnected to the normally lower filament loops, other wires extendingfrom the ends of said insulator and slidable on said supporting leads,the connection of said leads to said flare tube being rigidlfied by froman insulator tied to the ends of said leads,- with the lower portionsthereof hooked under the normally upper filament loops, said filament.

receiving energy from said leads through wires extending toward oneanother and fitting into coiled end sections of said filament, and aguiding bridge member comprising an insulator portion, hooked portionsextending from'said insulator portion and received in the normally lowerfilament loops, wires extending in a normally upward direction from theends of said insulator, and having eyes at their free ends through whichsaid supporting leads pass, said insulator having a depending guide wireslidably associated with a wire normally upstanding from said arbor, andwires extending outwardly from said arbor, wound around said leads withone or more turns, and having their free ends welded thereto.

9. An incandescent electric I lamp comprising a mount with a fiare tubeand an arbor, interior supporting leads extending from said tube, afilament supported between and receiving energy from said leads, andwires extending outwardly from said arbor, wound around said leads withone or more turns, and having their free ends welded thereto! 1 10. Afilament guiding member comprising a piece of glass cane with aplurality-of hooks extending laterally from one side and a guide wireextending in the opposite direction therefromf hooks depending from saidmember and supporting the upper loop and end portions of said filament,means connecting said end portions and leads, and a slidable guidemember suspended from the lower loops of said filament, said guidemember comprising a body portion, hooks ex-- tending from the sidesthereof, and engaging .said loops, and portions extending from the endsof said body portion, continued upwardly along the sides of saidfilament, and slidably engaging said leads, and means extendingdownwardly therefrom and slidably associated with said flare tube forpreventing tilting of said guide member.

12. An incandescent electricv lamp comprising a fiare tube, leadsextending upwardly therefrom, a filar ant positioned between said leads,said filament comprising a plurality of coil groups with their axesgenerally parallel and corresponding adjacent ends connected by loops,means comprising an insulator with wires extending from the ends thereofand tying together the free ends of said supporting leads, hooksextending from the lower side of said insulator and engaging the upperloop portions of said filament, and a sliding bridge member supportedfrom the lower loops of said filament, said bridge member comprising aninsulator with hooks extending upwardly from a side thereof and engagingthe lower filament loops, wires extending outwardly and upwardly andslidably engaging said leads on opposite sides of said filament, andmeans depending from a side of said bridge insulator and slidablyassociated with said flare tube.

13. A filament guide member comprising an insulator body portion with aplurality of hooks extending laterally from one side, a guide wireextending laterally from the other side, and a wire extending axiallyfrom each end and lat erally in the same general direction as the hooks,and provided at its end with a guiding loop.

HOWARD E. ALLEN.

